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37 /*! \defgroup module_domdec Spatial domain decomposition (for parallelization over MPI)
38 * \ingroup group_mdrun
40 * \brief Manages the decomposition of the simulation volume over MPI
41 * ranks to try to distribute work evenly with minimal communication
44 * \todo Get domdec stuff out of mdtypes/commrec.h
46 * \author Berk Hess <hess@kth.se>
50 /*! \libinternal \file
52 * \brief This file declares functions for mdrun to call to manage the
53 * details of its domain decomposition.
55 * \author Berk Hess <hess@kth.se>
57 * \ingroup module_domdec
60 #ifndef GMX_DOMDEC_DOMDEC_H
61 #define GMX_DOMDEC_DOMDEC_H
65 #include "gromacs/gpu_utils/devicebuffer_datatype.h"
66 #include "gromacs/math/vectypes.h"
67 #include "gromacs/utility/real.h"
71 struct gmx_domdec_zones_t;
72 struct gmx_localtop_t;
80 enum class PbcType : int;
83 class GpuEventSynchronizer;
87 struct AtomInfoWithinMoleculeBlock;
88 class DeviceStreamManager;
89 class ForceWithShiftForces;
91 class RangePartitioning;
92 class VirtualSitesHandler;
97 /*! \brief Returns the global topology atom number belonging to local atom index i.
99 * This function is intended for writing ASCII output
100 * and returns atom numbers starting at 1.
101 * When dd=NULL returns i+1.
103 int ddglatnr(const gmx_domdec_t* dd, int i);
105 /*! \brief Store the global cg indices of the home cgs in state,
107 * This means it can be reset, even after a new DD partitioning.
109 void dd_store_state(const gmx_domdec_t& dd, t_state* state);
111 /*! \brief Returns a pointer to the gmx_domdec_zones_t struct */
112 struct gmx_domdec_zones_t* domdec_zones(struct gmx_domdec_t* dd);
114 /*! \brief Returns the range for atoms in zones*/
115 int dd_numAtomsZones(const gmx_domdec_t& dd);
117 /*! \brief Returns the number of home atoms */
118 int dd_numHomeAtoms(const gmx_domdec_t& dd);
120 /*! \brief Returns the atom range in the local state for atoms that need to be present in mdatoms */
121 int dd_natoms_mdatoms(const gmx_domdec_t& dd);
123 /*! \brief Returns the atom range in the local state for atoms involved in virtual sites */
124 int dd_natoms_vsite(const gmx_domdec_t& dd);
126 /*! \brief Sets the atom range for atom in the local state for atoms received in constraints communication */
127 void dd_get_constraint_range(const gmx_domdec_t& dd, int* at_start, int* at_end);
129 /*! \libinternal \brief Struct for passing around the number of PME domains */
132 int x; //!< The number of PME domains along dimension x
133 int y; //!< The number of PME domains along dimension y
136 /*! \brief Returns the number of PME domains, can be called with dd=NULL */
137 NumPmeDomains getNumPmeDomains(const gmx_domdec_t* dd);
139 /*! \brief Returns the set of DD ranks that communicate with pme node cr->nodeid */
140 std::vector<int> get_pme_ddranks(const t_commrec* cr, int pmenodeid);
142 /*! \brief Returns the maximum shift for coordinate communication in PME, dim x */
143 int dd_pme_maxshift_x(const gmx_domdec_t& dd);
145 /*! \brief Returns the maximum shift for coordinate communication in PME, dim y */
146 int dd_pme_maxshift_y(const gmx_domdec_t& dd);
148 /*! \brief Return whether update groups are used */
149 bool ddUsesUpdateGroups(const gmx_domdec_t& dd);
151 /*! \brief Returns whether molecules are always whole, i.e. not broken by PBC */
152 bool dd_moleculesAreAlwaysWhole(const gmx_domdec_t& dd);
154 /*! \brief Returns if we need to do pbc for calculating bonded interactions */
155 bool dd_bonded_molpbc(const gmx_domdec_t& dd, PbcType pbcType);
157 /*! \brief Change the DD non-bonded communication cut-off.
159 * This could fail when trying to increase the cut-off,
160 * then FALSE will be returned and the cut-off is not modified.
162 * \param[in] cr Communication recrod
163 * \param[in] box Box matrix, used for computing the dimensions of the system
164 * \param[in] x Position vector, used for computing the dimensions of the system
165 * \param[in] cutoffRequested The requested atom to atom cut-off distance, usually the pair-list cutoff distance
167 bool change_dd_cutoff(t_commrec* cr, const matrix box, gmx::ArrayRef<const gmx::RVec> x, real cutoffRequested);
169 /*! \brief Set up communication for averaging GPU wait times over domains
171 * When domains (PP MPI ranks) share a GPU, the individual GPU wait times
172 * are meaningless, as it depends on the order in which tasks on the same
173 * GPU finish. Therefore there wait times need to be averaged over the ranks
174 * sharing the same GPU. This function sets up the communication for that.
176 void dd_setup_dlb_resource_sharing(const t_commrec* cr, int gpu_id);
178 /*! \brief Cycle counter indices used internally in the domain decomposition */
189 /*! \brief Add the wallcycle count to the DD counter */
190 void dd_cycles_add(const gmx_domdec_t* dd, float cycles, int ddCycl);
192 /*! \brief Communicate the coordinates to the neighboring cells and do pbc. */
193 void dd_move_x(struct gmx_domdec_t* dd, const matrix box, gmx::ArrayRef<gmx::RVec> x, gmx_wallcycle* wcycle);
195 /*! \brief Sum the forces over the neighboring cells.
197 * When fshift!=NULL the shift forces are updated to obtain
198 * the correct virial from the single sum including f.
200 void dd_move_f(struct gmx_domdec_t* dd, gmx::ForceWithShiftForces* forceWithShiftForces, gmx_wallcycle* wcycle);
202 /*! \brief Communicate a real for each atom to the neighboring cells. */
203 void dd_atom_spread_real(struct gmx_domdec_t* dd, real v[]);
205 /*! \brief Sum the contributions to a real for each atom over the neighboring cells. */
206 void dd_atom_sum_real(struct gmx_domdec_t* dd, real v[]);
208 /*! \brief Reset all the statistics and counters for total run counting */
209 void reset_dd_statistics_counters(struct gmx_domdec_t* dd);
211 /* In domdec_con.c */
213 /*! \brief Communicates the virtual site forces, reduces the shift forces when \p fshift != NULL */
214 void dd_move_f_vsites(const gmx_domdec_t& dd, gmx::ArrayRef<gmx::RVec> f, gmx::ArrayRef<gmx::RVec> fshift);
216 /*! \brief Clears the forces for virtual sites */
217 void dd_clear_f_vsites(const gmx_domdec_t& dd, gmx::ArrayRef<gmx::RVec> f);
219 /*! \brief Move x0 and also x1 if x1!=NULL. bX1IsCoord tells if to do PBC on x1 */
220 void dd_move_x_constraints(struct gmx_domdec_t* dd,
222 gmx::ArrayRef<gmx::RVec> x0,
223 gmx::ArrayRef<gmx::RVec> x1,
226 /*! \brief Communicates the coordinates involved in virtual sites */
227 void dd_move_x_vsites(const gmx_domdec_t& dd, const matrix box, rvec* x);
228 /*! \brief Communicates the positions and velocities involved in virtual sites */
229 void dd_move_x_and_v_vsites(const gmx_domdec_t& dd, const matrix box, rvec* x, rvec* v);
231 /*! \brief Returns the local atom count array for all constraints
233 * The local atom count for a constraint, possible values 2/1/0, is needed
234 * to avoid not/double-counting contributions linked to the Lagrange
235 * multiplier, such as the virial and free-energy derivatives.
237 * \note When \p dd = nullptr, an empty reference is returned.
239 gmx::ArrayRef<const int> dd_constraints_nlocalatoms(const gmx_domdec_t* dd);
241 /*! \brief Construct local state */
242 void dd_init_local_state(const gmx_domdec_t& dd, const t_state* state_global, t_state* local_state);
244 /*! \brief Construct the GPU halo exchange object(s).
246 * \param[in] mdlog The logger object.
247 * \param[in] cr The commrec object.
248 * \param[in] deviceStreamManager Manager of the GPU context and streams.
249 * \param[in] wcycle The wallclock counter.
251 void constructGpuHaloExchange(const gmx::MDLogger& mdlog,
253 const gmx::DeviceStreamManager& deviceStreamManager,
254 gmx_wallcycle* wcycle);
257 * (Re-) Initialization for GPU halo exchange
258 * \param [in] cr The commrec object
259 * \param [in] d_coordinatesBuffer pointer to coordinates buffer in GPU memory
260 * \param [in] d_forcesBuffer pointer to forces buffer in GPU memory
262 void reinitGpuHaloExchange(const t_commrec& cr,
263 DeviceBuffer<gmx::RVec> d_coordinatesBuffer,
264 DeviceBuffer<gmx::RVec> d_forcesBuffer);
267 /*! \brief GPU halo exchange of coordinates buffer.
268 * \param [in] cr The commrec object
269 * \param [in] box Coordinate box (from which shifts will be constructed)
270 * \param [in] coordinatesReadyOnDeviceEvent event recorded when coordinates have been copied to device
272 void communicateGpuHaloCoordinates(const t_commrec& cr,
274 GpuEventSynchronizer* coordinatesReadyOnDeviceEvent);
277 /*! \brief GPU halo exchange of force buffer.
278 * \param [in] cr The commrec object
279 * \param [in] accumulateForces True if forces should accumulate, otherwise they are set
281 void communicateGpuHaloForces(const t_commrec& cr, bool accumulateForces);
283 /*! \brief Wraps the \c positions so that atoms from the same
284 * update group share the same periodic image wrt \c box.
286 * When DD and update groups are in use, the simulation master rank
287 * should call this to ensure that e.g. when restarting a simulation
288 * that did not use update groups that the coordinates satisfy the new
291 * This function can probably be removed when even single-rank
292 * simulations use domain decomposition, because then the choice of
293 * whether update groups are used is probably going to be the same
294 * regardless of the rank count.
296 * \param[in] dd The DD manager
297 * \param[in] mtop The system topology
298 * \param[in] box The global system box
299 * \param[in] positions The global system positions
301 void putUpdateGroupAtomsInSamePeriodicImage(const gmx_domdec_t& dd,
302 const gmx_mtop_t& mtop,
304 gmx::ArrayRef<gmx::RVec> positions);